Oil-cooler arrangement in aircooled internal-combustion engine



June 3, 1952 SONDEREGGER 2,598,849

OIL COOLER ARRANGEMENT IN AIR-COOLED INTERNAL-COMBUSTION ENGINE Filed April 27, 1950 2 SHEETS-SHEET l Ion/a0 Jameerggger:

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June 3, 1952 SQNDEREGGER 2,598,849,

OIL COOLER ARRANGEMENT IN AIR-COOLED INTERNAL-COMBUSTION ENGINE Filed April 27, 1950 2 5HEETS$HEET 2 mam/r019:

Patented June 3, 1952 OIL-COOLER ARRANGEMENT IN AIR- COOLED INTERNAL COMBUSTION ENGINE Konrad Sonderegger, Winterthur, Switzerland,

assignor to Schweizerische Lokomotivund Maschinenfabrik, Winterthur, Switzerland Application April 27, 1950, Serial No. 158,532 In Switzerland May 11, 1949 2 Claims. (01. 123-4133) The present invention relates to air-cooled internal combustion engines of, which the finned cylinders are disposed in line and in which the cooling air supplied by a blower is led on to the cylinders in such a way that the said air is deflected into the transversal direction prior to flowing through the line of cylinders. In engines of this type it is diflicult to deliver the cooling air supplied by the blower, at a uniform rate and with minimum pressure loss to all the cylinders.

In a known arrangement ofthis character, the air-supply conduit is disposed laterally of the line of cylinders and is designed as a pressure chamber. Owing to the low air velocities arising in said chamber, it is readily possible to deliver the cooling air to the cylinders at uniform rate. The very large dimensions of said chamber, however, may prove of disadvantage in certain cases.

In order to smooth the said disadvantages, it has been proposed to reduce the dimensions of the said chamber to such extent that they will correspond approximately to the conventional contours of a normal engine. Such design, however, gives origin to high velocities of flow and disturbing eddies in the air-supply conduit. It has been'tried by the use of battles and constrictive means to obtain somewhat uniform part flows from such turbulent air stream. A uniform approach to the cylinder cooling-fins, however, is hardly obtainable by such means.

A further diificulty in air-cooled engines is presented by the disposition of the oil cooler. Two fundamentally different ways for arranging the oil coolers are known in the art: the cooler may be arranged either at the end of the cylinder line in order to be exposed to a part stream of the cooling-air flow, or upstream or downstream of the fan where the cooler is washed by the entire flow of cooling air.

In the first of said latter arrangements it is of disadvantage that the volume of cooling air required for the oil cooler, has to be produced additionally, i. e. that it is of no value for cooling the cylinders. In the second arrangement it is of disadvantage that the oil cooler has to be made comparatively deep in order to be accommodatable within the cross-section of the main cooling stream and that, therefore, the oil cooler presents a considerable obstacle to the air stream.

The present invention envisages the combination of the means for uniformly distributing the air with the means for oil cooling, but avoiding the disadvantages inherent to each of said means. According to the present invention, the vertical plane passing through the center of the finned oil plane through the cylinders, and the oil cooler is disposed in the cooling-air supply-conduit beside the cylinder line so that the cooler fins at the same time function as deflector vanes for the stream of cooling air. I

Itis a particular advantage of the present invention that the oil cooler does not require any additional space of the machine, and that owing to the obliquity of the oil cooler, the latter may be provided with a large end face and be made of a correspondingly small depth. A further ad vantage is that the oil cooler fins subdivide the stream of cooling air into a great number of parallel currents so that. the airflow past the oil cooler is practically free of whirls.

Two forms of invention are illustrated in the accompanying drawing inwhich:

Fig. 1 shows an air-cooled internal combustion engine fitted with a first form of invention,

Fig. 2 a cross-section on the line IIII of Fig. 1,

Fig- 3 a horizontal section on the line IIIIII of Fig. 1, H

Fig. 4 a second form in cross-section in the left-, hand portion and in elevation in the right-hand portion,

Fig. 5 fragmentary plan view of a first modification of the oil cooler design, and

Figs. 6 and 7 a second modification of theoil cooler in a cross-section and fragmentary longitudinal section respectively.

In the first form (Figs. 1-3) the engine comprises four separate cylinders l disposed in line and provided with cooling fins 2 standing at right angles to the cylinder axes. The intake and exhaust valves (not shown) are controlled by the cam shaft 3 which is driven by the crankshaft 4. The cooling-air fan 5 is disposed on the forward lateral end of the engine, approximately at the level of the cylinder midpoints. The impeller B of which the axis is arranged parallel to that of the crankshaft 4, is driven from the latter through V-belts I. An air intake nozzle 8 involving a system of guide vanes 9, is situated upstream of fan 5. Downstream of the latter, an air duct ill is secured by screws to the cylinders l and the engine casing, through which duct the cooling air flows to the cylinders.

An oilcooler H is disposed inside the air duct ii], at an angle to the line of cylinders. The vertical plane passing through the longitudinal axis of the oilcooler II and the vertical plane passing through the cylinder axes intersect each other along a vertical line IT. The oilcooler I l comcooler is washed by the entire stream 6f ceoli air, the latter being deflected through the fins Ida from a longitudinal direction into a transverse direction and then passing through the line of cylinders. fins act similarly to the deflecting vanes of aw-i'nd canal. They perform a combing action on the air stream so as to prevent the occurrence of eddies. The mass flow, therefore, is uniformly distributed onto the individual cylinders, shame latter are uniformly washed by the cooling air.

Since the oilcooler, due to its inclined position in the air duct, may be made comparatively long, a slight cooler depth will prove sufficient for producing the required cooling surface. Such feature has a favorable effect on the flow conditions of the cooling-air stream in that such a cooler offers only a slight resistance to the air stream.

A further advantage resides in the fact that the entire arrangement saves space, for the air duct projects only slightly beyond the engine block and no separate space is required for accommodating the oilcooler, since the latter is situated within the cooling-air duct.

In the second form of invention, shown in ff-jig. 4, the engine also comprises a plurality of verti cal, separate, finned cylinders arranged in line, which drive the crankshaft 2|. The cooling air, however, is not supplied through a fan disposed at the level of the cylinder midpoints, but through a flywheel 22 which for such purpose is built in known manner as centrifugal impeller. Since such impeller is situated at a lower level than the cylinders 20, the cooling air has to be upwardly conducted to wash the cylinder coolingfins 23. For such purpose, a riser 25 is connected to the scroll case 24, which riser in its upper portion is formedby the cowl 26 which is flanged to the cylinders. The tubular 'oil cooler 28 is provided with fins 21 and is disposed in the riser 25 at the same point as in the first form where the cooling air has to be deflected in order to subsequently flow between the cylinders 20 in transverse directions. For such purpose the In this arrangement, the oil cooler 7 longitudinal median plane of the oil cooler ineludes an acute angle with that of the line of cylinders, and the two planes intersect each other on a straight line (29) which is parallel to the crankshaft axis. As indicated by the arrows in Fig. 4, the cooling-air stream in this form er arrangernent also is subdivided into a plurality of individual currents by the oilcooler fins 21-, whieh currents are parallel inter se and how towards the cylinder cross-fins practically free of eddies.

The entire fan-and-airduct assembly could be arranged, e. g., above the line of cylinders, in which case the cylinders were washed by the cooling-air stream in a downward direction, the cylinder coining-fins being arranged and formed accordingly. Further, the oilcooler fins could be made arcuate instead of straight as shown for example. in Fig. 5 for the fins I5a of the oil-'' cooler tubes I5. Such modified arrangement will not alter the favorable cooling effect of the fins, biit permit or; the other hand to still better adapt the fins to their function as deflectors in that the now resistance thereby is further reduced an'dlthe cooling air is still better conducted. up to the line of cylinders. In order to facilitate the supervision of the oilcooler, a window or cover I6 may be provided on the air-duct cowl I0.

In 6 and 7 a commercially available type of 'o'ilco'oler is shown for example, in which the oil tubes 30 are provided with circular fins 30a, the fins of two adjacent tubes being interleaved. In this simple construction, the oilcooler also may be used for deflecting the stream of cooling air.

The present invention, of course, also may be applied to in-lin'e engines of V-arrangement or of boxer arrangement.

Depending on the general construction of the engine in question, one or the other main forms of the present invention, involving the disposition of the 'oilcooler, will be preferable.

What I'claim as new 1. In an air-cooled internal combustion engine of which the cylindersare in line, comprising a ducted fan for supplying the cooling air to the cylinders, a finned oil-cooler, and duct means for transversely deflecting the air supplied by said fan before its passage between the cylinders, the improvement defined by arranging the oil-cooler in the cooling-air duct in such position that the oil-cooler fins are inclined to the direction of flow of the cooling air stream, whereby the oilcooler fins act as deflector vanes for the flow of cooling air.

2. In an oil-cooler arrangement as set cut in claim 1, the'impro'vement defined by making the oil-cooler fins of arc'uate form to thereby facilitate the deflection of the cooling-air stream.

' KONRAD SONDEREGGER.

REFERENCES CITED The following references are of record in the file of this atent:

UNITED STATES PATENTS Number Name Date 2,267,423 Reimspiess Dec. 23, 1941 2,274,442 Woods Feb. 24, 1942 

